Spinning artificial silk



8, 9 P. F. c. SOWTER ETAL 2,304,212

SPINNING ARTIFICIAL SILK Filed March 11, 1941 INVENTORS PECSOWTER PW)W.DD. HARRIES ATTORNEYS Patented Dec. 8, 1942 SPINNING ARTIFICIAL SILKPercy Frederick Combe Sowter and William Dan Douglas Harries, Spondon,near Derby, England, assignors to Celanese Corporation of America, acorporation of Delaware Application March 11, 1941, Serial No. 382,680

' In Great Britain April 25, 1940 8 Claims. (01. 18-54) This inventionrelates to the centrifugal spinning of artificial silk, and isparticularly concerned with facilitating removal of cakes of yarn fromspinning-pots.

In the centrifugal spinning of wet yarn o artificial filament it isdesirable that the spun cakes should be removed from the spinning-pot assoon as possible after dofiing. A delay of only one day in freeing thecakes from the pots results in the hold-up of several pots per spindle,while to dry the cakes in the pots might, owing to the limited amount ofsurface exposed, take a week or more. In the case of cellulose acetateor other cellulose ester or. ether yarns difficulty is found inobtaining a quick and easy release of the cakes from the spinning pots,.in spite of the walls of the pots being usually provided with a sharptaper. This is especially true of such yarns as have been prepared byextrusion of the spinning solution into a coagulating bath containing ahigh concentration of a solvent for the cellulose ester or ether, andmaybe by subjecting the yarn to stretching, as described, for example,in U. S. Patents Nos. 2,147,640 and 2,086,122. Thus, it is found that acake of cellulose acetate yarn which has been produced using aqueousdiethylene-glycol diacetate, as the coagulant, cannot be removed fromthe pot without damage even after standing several days.

The close adhesion of the yarn to the spinning pot is probably due tothe perfect contact set up between the soft yarn and the walls of thepot. Air is excluded and a suction effect is obtained on attempting towithdraw the cake. With a viscose yarn the problem is not so acute since1 the cake readily shrinks from the Walls of the spinning-pot afterstanding for a short time.

It has now been found that removal of the cake of yarn from thespinning-pot is facilitated by running into the spinning pot anadditional end of yarn, preferably coarse, dry yarn, at the commencementof spinning, the additional yarn conveniently being run together withthe wet yarn. The supply of this additional yarn can be stopped after ashort time, for example 30-60 seconds. In this way, a relatively coarselayer of doubled yarn is formed at the surface of the cake adjacent tothe wall of the spinning-pot. The surface is thus broken and the suctioneffect produced on attempting to remove the cake'is avoided. a

Best results are obtained using as the additional yarn one of heavydenier compared with the. wet spun yarn. Thus, a dry yarn of about fordOllbling with a freshly spun yarn of about 100- 50 denier.

It is desirable that the additional yarn should.

be of-a smooth character such as obtains in continuous filament yarns,for example yarns of dryor wet-spun cellulose acetate or other cellulosederivative, or natural silk. Yarn made from staple fibres, e. g., Woolor cotton, is not generally satisfactory .slnce it is apt either-toadhere to the Walls of the pot or to form "bridges in the cake, 1. e.,lengths of yarn drawn tight inside the spinning pot so as to form achord to the circle of which the main cake of yarn is the circumference.Its springy nature makes wool 3, yarn particularly prone to this latterdefect.

One, two or more ends of the additional yarn can be doubled in; forexample the formation of the cake may be started by running into thespinning funnel two ends of dry 300 denier cellulose acetate yarn witheach freshly spun end of 100*150 denier cellulose acetate yarn. emergingfrom the coagulating bath. The dry ends can be broken out after 30-60seconds, i. e. after the first few metres of freshly spun yarn have beentaken up in the spinning-pot. The doubled yarn thus formed at thesurface of the cake considerably facilitates the removal of the latterfrom the spinning-pot.

If desired, a heavier coating of doubled yarn than is strictly necessaryto facilitate removal of the cake from the pot may be provided. This wetspun yarns Whether derived from cellulose apparatus;

and its derivatives or from synthetic fibre-forming polymers, forexample polyhexamethylene adipamide.

The accompanying drawing shows diagrammatically the carrying-out of theinvention,

Fig. 1 being a side elevation of a wet-spinning Fig, 2 a cross-sectionthrough a spinningpost in which winding of the cake has been completed;and

Fig. 3 a view similar to Fig. 2 showing the removal of the cake from theinverted pot.

In Fig. 1, a Wet-spun cellulose acetate thread l is drawn from thespinning apparatus 2 by a feed roller 3 and delivered to a spinning-pot4 300 denier has been found to be very satisfactory 55 through a funnel5. A conveniently placed bobbin 6 enables a thread I of dry celluloseacetate (e. g., 2-fold 140-150 denier) to be run into the pot 5 alongwith the thread i at the beginning of the winding operation. In 30-60seconds, a layer 8 of the coarse material formed by the two threads l, lis built insidethe pot. l is then broken and the thread I is built intothe cake 9 inside the layer 8.

As Fig. 2 indicates diagrammatically, the coarse thread forming thelayer 8'prevents the outer surface of the cake 9 from making veryintimate contact with the inside surface of the pot 4. Consequently,when the pot 4 is inverted on to a surface l0 and withdrawn (as shown inFig. 3), the cake 9 is released. If necessary, the pot may be bumped onthe surface, but sometimes the cake will nearly fall out under its ownweight, especially if it has been kept in the pot for a few hours.

Having described our invention, what we desire to secure by LettersPatent is:

1. In the centrifugal spinning of wet yarn of artificial filaments bymeans of a spinning-pot, running an additional yarn into the pot at thecommencement of spinning to form a layer that facilitates the removal ofthe cake of yarn wound in the pot.

2. An operation according to claim 1, wherein the additional yarn is adry yarn.

3. In the centrifugal spinning of wet yarn of cellulose derivativeartificial filaments by means of a spinning-pot, running an additionalyarn into the pot at the commencement of spinning'to form a layer thatfacilitates the removal of the cake of yarn wound in the pot. I

4. In the centrifugal spinning of wet yarn of cellulose acetateartificial filaments by meansof a spinning-pot, running an additionaldry The thread the commencement of spinning to form a layer thatfacilitates the removal of the cake of yarn wound in the pot.

5. In the centrifugal spinning of wet yarn of cellulose acetateartificial filaments by means of a spinning-pot, running an additionalcoarse yam, together with the wet yarn, into the pot at the commencementof spinning to form a layer that facilitates the removal of the cake ofyarn wound in the pot,

6. In the centrifugal spinning of wet yarn of cellulose acetateartificial filaments by means of a spinning-pot, running an additionalcontinuous filament yarn together with the wet yarn, into the pot at thecommencement of spinning to form a layer that facilitates the removal ofthe cake of yarn wound in the pot.

'7. In the centrifugal spinning by means of a spinning-pot of wet yarnof cellulose acetate artificial filaments which has been produced byextruding a solution of cellulose acetate into a spinningbath containinga high concentration of solvent for the cellulose acetate, running anadartificial filaments which has been produced by extruding a solutionof cellulose acetate into a spinning bath containing aqueousdiethyleneglycol diacetate, running an additional continuous filamentyarn together with the wet yarn into the pot at the commencement ofspinning to form a layer that facilitates the removal of the cake ofyarn wound in the pot.

PERCY FREDERICK CQMBE SOW'I'ER. WILLIAM DAN DOUGLAS HARRIES.

